This invention relates to an apparatus for unrolling and spreading rolled cloth and, more particularly, to an apparatus for unrolling and spreading rolled cloth, which stably spreads rolled cloth with a simple construction.
Generally, cloth is rolled into a large roll. For cutting the rolled cloth, preparatory work is needed in which the cloth is unrolled, spread, cut a desired length, and stacked or folded. To this end, a rolled cloth spreading apparatus has been developed. In the apparatus, an elongated work table is set horizontally, a spreader is movable in the longitudinal direction of the work table. A long roll of cloth is rotatably set in the spreader in a suspended fashion, while being located at a predetermined distance from the foward end of the spreader as viewed in the advance direction thereof. The rotatably suspended cloth is unrolled by a roller, operationally coupled with a drive motor, and spread on the work table. During the course of the unrolling and spreading operation, tension is generated in the roll of cloth and the unrolled cloth. Particularly, when the cloth is thin, the tension causes wrinkles on the unrolled cloth or impedes the unrolling operation because the thin cloth is resiliently expanded or contracted. When thick cloth such as denim or shynthetic leather is rolled into a roll with a large diameter, a relatively large force is required at the initial stage of unrolling the cloth; hence, slippage tends to occur between the cloth and the delivery roll. This makes it difficult to unroll the cloth at a fixed amount per unit time.
There is a proposal to solve this problem. In the proposal, two individual drive motors are separately provided. One is for driving the roll to roll the woven cloth into a roll of cloth and to unroll the rolled one. The other is for driving a delivery roll to deliver the unrolled cloth for spreading and to deliver the woven cloth for rolling into a cloth roll. In operation, both the motors are rotated in a synchronizing manner, thereby automatically effecting the preparatory work. In spreading the cloth, both the motors must be rotated in synchronism with the running of the spreader. To this end, when the rolled cloth is taken out, wheels of the spreader are mechanically disconnected from the drive shafts thereof by means of an electromagnetic clutch. Then, the disconnected drive shaft is mechanically connected to the roll-up roll and the delivery roll by means of a chain or a gear for providing the synchronous rotation of the rolls. In this case, even if both the rolls are synchronous in operation to have fixed periphery speeds, the unrolled and spread cloth is frequently trailed. Specifically, the cloth with variously different natures is actually handled. Because of this, inertia of the rolled cloth differs for each cloth. The difference of the cloth inertia gives rise to slippage between the dispensing roller and the rolled cloth and between the dispensing roller and the cloth. As a result, the unrolled cloth is not coincidence in length with the running distance of the spreader. In this way, cloth trailing occurs.
To solve this, a mechanical nonstep transmission is coupled with the drive shafts for the wheels of the spreader, the delivery roll, and the roll-up roll. According to the nature of the cloth used, a change gear ratio of each change gear is changed in the range of 0.8-1.2. This approach goes well as long as the rotating speed thereof is invariable. In actual use, however, it is difficult to keep the transmission gear ratio at a fixed value because the spreader frequently repeats start, acceleration, deceleration, and stop, and particularly in repeatedly spreading the rolled cloth, the forward and reverse motions of the unrolling machine are alternately repeated. Additionally, slippage occurs between the wheels and the related rails. A variation of the transmission gear ratio due to slippage and a change of the weight of the cloth also brings about that inequality problem of the running distance of the spreader to the length of the unrolled cloth, even if the change gear ratio is optimumly adjusted according to the nature of the cloth and the result of observing the unrolling state of the cloth. This results in trailing or slackening of the cloth due to excessive take-out thereof.
To eliminate the adverse effect on the cloth by the inertia, an additional motor is provided for driving the dispensing roller in an unroll mode. A conveyor interlocked with the delivery roll is provided under the dispensing roller. A distance roll is provided at the midpoint therebetween and controls the motor for driving the dispensing roller. This approach, however, is complicated in structure and instable in operation.